The invention concerns a catalyst component for an alpha olefine polymerizing catalyst which comprises an organo-aluminum compound and electron donor, and a solid catalyst component which is obtained when a compound containing magnesium has reacted with a titanium halide compound. The present invention is also directed to a procedure for manufacturing this catalyst component, and to a procedure for polymerizing alpha olefines, especially propylene, which makes use of the catalyst component.
Catalysts known in the prior art with high activity for polymerizing alpha olefines, which have been manufactured include an aluminum alkyl compound, an electron donor, and a halogenated titanium compound on a carrier substance comprising various magnesium compounds. Chlorinated magnesium compounds have generally been used as the magnesium compound, which may be, for instance, water-free magnesium chloride alone or together with other magnesium compounds, or an organic magnesium compound which has been prepared by halogenating organic magnesium compounds with the aid of chlorine-containing compounds.
In polymerizing catalysts of this type, the properties of the solid carrier component have significant influence upon the properties of the ultimate catalyst, e.g. upon its activity. These properties can be substantially influenced through the mode of manufacturing of the carrier component.
The present invention concerns a catalyst in whict the carrier component has been prepared from minerals containing magnesium and aluminum, which may be natural or synthetic minerals. An example of this type of mineral is hydrotalsite, and its composition is indicated by the following formula:
ti Mg.sub.4 Al.sub.2 (OH).sub.12 CO.sub.3 3H.sub.2 O
Hydrotalsite also occurs in several other forms. Thus, Mg.sub.4.5 Al.sub.2 (OH).sub.13 4H.sub.2 O, Mg.sub.2 Al.sub.2 (OH).sub.8 CO.sub.3 3H.sub.2 O and Mg.sub.6 Al.sub.2 (CO.sub.3) (OH).sub.16 4H.sub.2 O are also hydrotalsites. Other minerals containing magnesium and aluminum are, for instance, indigirite Mg.sub.2 Al.sub.2 (CO.sub.3).sub.4 (OH).sub.2 15H.sub.2 O and manassite Mg.sub.6 Al.sub.2 (CO.sub.3)(OH).sub.16 4H.sub.2 O.
Magnesium minerals have been used as starting material in preparing inert carrier components for Ziegler-Natta catalysts for the purpose of polymerizing olephines. In DE Patent No. 2,614,325, a procedure is disclosed in which hydrotalsite is calcinated by heating for several hours at high temperature, whereby it is totally converted into a mixture of magnesium and aluminum oxides, which is totally water-free. Catalyst carriers have been prepared from this mixture, by treating the same with titanium tetrachloride, after which an active Ziegler-Natta catalyst has been obtained for the purpose of polymerizing olefines, especially ethylene.
As disclosed in DE Patent No. 3,036,450, polymerizing catalysts have been prepared from hydrotalsite by mixing the same in hexane at room temperature. A solid substance is then added, which has been obtained by grinding magnesium chloride for several hours in the presence of titanium tetrachloride in a nitrogen atmosphire. Catalysts prepared in this manner are applied for polymerizing ethylene, which is not as sensitive to the effect of moisture as propylene polymerizing. If the catalyst carrier contains water, then a catalyst is obtained which is inactive in propylene polymerizing.
It has turned out to be difficult to manufacture from hydrotalsite and equivalent mineralcontaining aluminum, active Ziegler-Natta catalysts, in particular those for the polymerizing of propylene, because in these processes the catalysts are extremely sensitive to moisture and to the crystal water present in the carrier. Even minimal quantities of crystal (crystallized) water already lower the activity of the catalyst significantly. This is probably due to the aluminum in the mineral, which impairs the activity of the catalyst and inhibits liberation of the crystal water from the carrier.